ORCID Profile
0000-0002-3024-2380
Current Organisations
Woolcock Institute of Medical Research
,
Royal North Shore Hospital
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Publisher: Wiley
Date: 03-09-2020
DOI: 10.1111/RESP.13688
Abstract: Fixed airflow obstruction (FAO) in asthma occurs despite optimal inhaled treatment and no smoking history, and remains a significant problem, particularly with increasing age and duration of asthma. Increased lung compliance and loss of lung elastic recoil has been observed in older people with asthma, but their link to FAO has not been established. We determined the relationship between abnormal lung elasticity and airflow obstruction in asthma. Non-smoking asthmatic subjects aged >40 years, treated with 2 months of high-dose inhaled corticosteroid/long-acting beta-agonist (ICS/LABA), had FAO measured by spirometry, and respiratory system resistance at 5 Hz (Rrs Eighteen subjects (11 males mean ± SD age: 64 ± 8 years, asthma duration: 39 ± 22 years) had moderate FAO measured by spirometry ((mean ± SD z-score) post-bronchodilator FEV Increased lung compliance and loss of elastic recoil relate to airflow obstruction in older non-smoking asthmatic subjects, independent of ageing. Thus, structural lung tissue changes may contribute to persistent, steroid-resistant airflow obstruction. ACTRN126150000985583 at anzctr.org.au (UTN: U1111-1156-2795).
Publisher: Wiley
Date: 18-05-2018
DOI: 10.1111/RESP.13326
Publisher: Wiley
Date: 21-03-2019
DOI: 10.1111/RESP.13532
Publisher: Wiley
Date: 11-09-2022
DOI: 10.1111/RESP.14357
Abstract: No abstract available.
Publisher: American Physiological Society
Date: 11-2019
DOI: 10.1152/JAPPLPHYSIOL.00304.2019
Abstract: Pulmonary electrical impedance tomography (EIT) is a functional imaging technique that allows real-time monitoring of ventilation distribution. Ventilation heterogeneity (VH) is a characteristic feature of chronic obstructive pulmonary disease (COPD) and has previously been quantified using features derived from tidal variations in the litude of the EIT signal. However, VH may be better described by time-based metrics, the measurement of which is made possible by the high temporal resolution of EIT. We aimed 1) to quantify VH using novel time-based EIT metrics and 2) to determine the physiological relevance of these metrics by exploring their relationships with complex lung mechanics measured by the forced oscillation technique (FOT). We performed FOT, spirometry, and tidal-breathing EIT measurements in 11 healthy controls and 9 volunteers with COPD. Through offline signal processing, we derived 3 features from the impedance-time ( Z- t) curve for each image pixel: 1) t E , mean expiratory time 2) PHASE, mean time difference between pixel and global Z- t curves and 3) AMP, mean litude of Z- t curve tidal variation. Distribution was quantified by the coefficient of variation (CV) and the heterogeneity index (HI). Both CV and HI of the t E and PHASE features were significantly increased in COPD compared with controls, and both related to spirometry and FOT resistance and reactance measurements. In contrast, distribution of the AMP feature showed no relationships with lung mechanics. These novel time-based EIT metrics of VH reflect complex lung mechanics in COPD and have the potential to allow real-time visualization of pulmonary physiology in spontaneously breathing subjects. NEW & NOTEWORTHY Pulmonary electrical impedance tomography (EIT) is a real-time imaging technique capable of monitoring ventilation with exquisite temporal resolution. We report novel, time-based EIT measurements that not only demonstrate ventilation heterogeneity in chronic obstructive pulmonary disease (COPD), but also reflect oscillatory lung mechanics. These EIT measurements are noninvasive, radiation-free, easy to obtain, and provide real-time visualization of the complex pathophysiology of COPD.
Publisher: Informa UK Limited
Date: 25-05-2018
DOI: 10.1080/15412555.2018.1458217
Abstract: Hyperinflation, gas trapping and their responses to long-acting bronchodilator are clinically important in COPD. The forced oscillation technique (FOT) measures of respiratory system resistance and reactance are sensitive markers of bronchodilator response in COPD. The relationships between changes in resistance and reactance, and changes in hyperinflation and gas trapping, following long-acting bronchodilator (LA-BD) have not been studied. 15 subjects with mild-moderate COPD underwent FOT, spirometry then body plethysmography, before and 2 hours after a single 150 microg dose of the LA-BD indacaterol. Hyperinflation was quantified as the inspiratory capacity to total lung capacity ratio (IC/TLC), and gas trapping as residual volume to TLC ratio (RV/TLC). At baseline, FOT parameters were moderately correlated with IC/TLC (|r| 0.53-0.73, p < 0.05). At 2 hours post-LA-BD, there were moderate correlations between change in FOT and change in RV/TLC (|r| 0.60-0.82, p < 0.05). Baseline FOT parameters also correlated with the subsequent post-LA-BD change in both IC/TLC (|r| 0.54-0.62, p < 0.05) and RV/TLC (|r| 0.57-0.76, p < 0.05). FOT impedance reflects hyperinflation and gas trapping in COPD, and the potential for long-acting bronchodilator responsiveness. These results provide us with further insight into the physiological mechanisms of action of long-acting bronchodilator treatment, and may be clinically useful for predicting treatment responses.
Publisher: Wiley
Date: 09-01-2018
DOI: 10.1111/RESP.13251
Abstract: Severe asthma is defined by the high treatment requirements to partly or fully control the clinical manifestations of disease. It remains a problem worldwide with a large burden for in iduals and health services. The key to improving targeted treatments, reducing disease burden and improving patient outcomes is a better understanding of the pathophysiology and mechanisms of severe disease. The heterogeneity, complexity and difficulties in undertaking clinical studies in severe asthma remain challenges to achieving better understanding and better outcomes. In this review, we focus on the structural, mechanical and inflammatory abnormalities that are relevant in severe asthma.
Publisher: Springer Science and Business Media LLC
Date: 11-02-2016
DOI: 10.1038/PR.2016.24
Abstract: Intrauterine growth restriction (IUGR) refers to the situation where a fetus does not grow according to its genetic growth potential. One of the main causes of IUGR is uteroplacental vascular insufficiency. Under these circumstances of chronic oxygen and nutrient deprivation, the growth-restricted fetus often displays typical circulatory changes, which in part represent adaptations to the suboptimal intrauterine environment. These fetal adaptations aim to preserve oxygen and nutrient supply to vital organs such as the brain, the heart, and the adrenals. These prenatal circulatory adaptations are thought to lead to an altered development of the cardiovascular system and "program" the fetus for life long cardiovascular morbidities. In this review, we discuss the alterations to cardiovascular structure, function, and control that have been observed in growth-restricted fetuses, neonates, and infants following uteroplacental vascular insufficiency. We also discuss the current knowledge on early life surveillance and interventions to prevent progression into chronic disease.
Publisher: Wiley
Date: 04-2021
DOI: 10.1111/RESP.14053
Abstract: Asthma guidelines emphasize the importance of assessing lung function and symptoms. The forced oscillation technique (FOT) and its longitudinal relationship with spirometry and symptoms are unresolved. We examined concordance between longitudinal spirometry, FOT and symptom control, and determined FOT limits of agreement in stable asthma. Over a 3‐year period, adults with asthma attending a tertiary clinic completed the asthma control test (ACT), fraction of exhaled nitric oxide (FeNO), FOT and spirometry. Analysis included between‐visit concordance for significant change using Cohen's kappa ( κ ) and stable asthma FOT limits of agreement. Data ( n = 186) from 855 visits (mean ± SD 4.6 ± 3.0 visits), 114 ± 95 days apart, were analysed. Between‐visit concordance was moderate between reactance at 5 Hz ( X 5) and forced expiratory volume in 1 s (FEV 1 ) ( κ = 0.34, p = 0.001), and weak between ACT and FEV 1 ( κ = 0.18, p = 0.001). Change in FeNO did not correlate with lung function or ACT ( κ 0.05, p 0.1). Stable asthma between visits ( n = 75 132 visits) had reduced lung function variability, but comparable concordance to the entire cohort. Limits of agreement for FEV 1 (0.42 L), resistance at 5 Hz (2.06 cm H 2 O s L −1 ) and X 5 (2.75 cm H 2 O s L −1 ) in stable asthma were at least twofold greater than published values in health. In adults with asthma, there is moderate concordance between longitudinal change in FOT and spirometry. Both tests relate poorly to changes in asthma control, highlighting the need for multi‐modal assessment in asthma rather than symptoms alone. The derivation of longitudinal FOT limits of agreement will assist in its clinical interpretation.
Publisher: Wiley
Date: 17-02-2022
DOI: 10.1111/RESP.14218
Abstract: Oxygen is a life-saving therapy but, when given inappropriately, may also be hazardous. Therefore, in the acute medical setting, oxygen should only be given as treatment for hypoxaemia and requires appropriate prescription, monitoring and review. This update to the Thoracic Society of Australia and New Zealand (TSANZ) guidance on acute oxygen therapy is a brief and practical resource for all healthcare workers involved with administering oxygen therapy to adults in the acute medical setting. It does not apply to intubated or paediatric patients. Recommendations are made in the following six clinical areas: assessment of hypoxaemia (including use of arterial blood gases) prescription of oxygen peripheral oxygen saturation targets delivery, including non-invasive ventilation and humidified high-flow nasal cannulae the significance of high oxygen requirements and acute hypercapnic respiratory failure. There are three sections which provide (1) a brief summary, (2) recommendations in detail with practice points and (3) a detailed explanation of the reasoning and evidence behind the recommendations. It is anticipated that these recommendations will be disseminated widely in structured programmes across Australia and New Zealand.
No related grants have been discovered for Gregory King.